The retina is the innermost layer of the eye. It is an essential layer responsible for sending the signals to the brain received when we see an object. It is made up of two different cells called rods and cones. Rods are responsible for vision in dim light and. Cones are responsible for daylight and colour vision.
Figure 1 : The cone and rod cells present in the retina
Pic Courtesy: https://www.istockphoto.com/vector/anatomy-of-photoreceptor-cells-gm1223394024-359350216
The retina is an essential layer of the eye, which, when affected, can lead to permanent vision loss. In this review, we will see some of the common retinal conditions.
Diabetic Retinopathy(DR)
Figure 2: Normal eye V/s an eye with diabetic retinopathy
Pic Courtesy: https://www.istockphoto.com/vector/anatomy-of-normal-eye-and-diabetic-retinopathy-gm695338058-128668563
Diabetic retinopathy is a complication of diabetes that causes blurring of vision and can lead to blindness if left untreated. It is common in India as the number of diabetic patients in India is high and is increasing day by day.
In a survey done by the Union Health Ministry, about 16.9% had DR. Diabetes mellitus is a condition that can damage many organs of the body at a time. Irrespective of the type of diabetes, these patients have a higher risk of developing this condition.
In diabetic retinopathy, the increased blood sugar tends to block the blood vessels of the eye, which supply blood to the retina. As the blood supply is blocked, the retina develops tiny new and weak vessels. These new vessels can leak and bleed anytime, leading to blindness.
One effective way to prevent this condition is by good control of your blood sugar level. Controlling your sugar level helps to lower the risk of developing vision loss.
Patients with DR often experience symptoms like blurred vision, floating particles in front of their eyes. This condition does not have severe symptoms in the early stages of the disease. Hence, it is crucial to get your retina examined regularly by an ophthalmologist who is a retina specialist, once every year.
Age-Related macular degeneration(ARMD)
Age-related macular degeneration is a condition that affects the centre part of the retina, called the macula. The macula is rich in cones responsible for day and central vision. Any damage to the macula can lead to loss of central vision. With central vision loss, it is harder to see people’s faces or do any work.
As the name suggests, it is age-related, which means it is associated only with older people. People who are older than 50 years, obese, smoke, high blood pressure, and have a family history of ARMD are at the risk of developing ARMD.
There are two forms of macular degeneration, dry and wet. In the dry form, tiny yellow deposits (drusen) settle under the retina. These drusens, when small, cause no visual problems, but as they grow in size, they disturb the central vision.
New blood vessels are formed and grow under the macula in the wet form. These blood vessels leak and bleed under the macula, thereby blocking the vision.
Thus, older people have to have a regular eye check-up at least once a year.
Retinopathy of Prematurity (ROP)
Figure 3: Normal Retina versus Underdeveloped Retina
Retinopathy of Prematurity occurs in premature infants. As the baby is premature, not all the body parts will be developed completely. Likewise, the retina of premature children remains undeveloped at the time of birth. This is one of the leading causes of childhood blindness and can lead to permanent vision loss if left untreated.
Smaller the baby, the higher the risk of developing ROP. Babies born before 32 weeks or weigh less than 1500 grams should be screened for ROP without fail.
Retinal Detachment (RD)
Retinal detachment is when the retina is pulled away from its normal position. Imagine a tree getting detached from its roots. Once the tree is detached, the tree loses its function and cannot nourish itself. Likewise, the pulled-away retina also loses its function. If your retina is detached, you might notice small black spots in your vision called floaters or a curtain or shadow which hides your vision.
This condition is an ocular emergency. Thus if you experience any of these visual disturbances, visit a nearby ophthalmologist at the earliest. There are various causes for this retinal detachment. Some of them are ageing, injury to the eyes, high minus power, previous eye surgery, etc.
There are three different types of retinal detachment, each with its different reason for the detachment.
Rhegmatogenous retinal detachment
In rhegmatogenous, any holes or tears in the retina allow the fluid to enter the retina, thereby causing detachment.
Tractional retinal detachment
Tractional RD occurs when any tissue pulls the retina from its position.
Exudative retinal detachment.
Exudative is when the fluid settles beneath the retina and pulls it without any holes and tears. There are different treatment options to treat this condition, such as injecting oil or gas inside the eye to help the detached retina get attached.
Retinal Vascular occlusions
The retina is a layer that needs a constant supply of nutrients and oxygen. The retinal arteries are blood vessels responsible for carrying blood to the retina. Those who drain or take away the impure blood from the retina are called retinal veins.
Suppose there is any blockage in either of the arteries or veins. In that case, it is called a retinal artery occlusion and retinal vein occlusion, respectively. People with retinal vascular occlusions may experience sudden or gradual painless loss of vision.
Retinal artery occlusion (RAO)
Figure 4: represents a normal retinal artery and a blockage in the artery.
The retina is supplied by the main artery called the central retinal artery. There are two types of Retinal artery occlusion:
Central and Branched.
In Central Retinal Artery Occlusion (CRAO), the main artery responsible for the eye gets blocked. It causes sudden painless loss of vision.
Branched Retinal Artery Occlusion (BRAO) occurs when only a small branch of the central retinal artery is blocked, leading to vision loss in a particular section.
Retinal artery occlusion could be caused due to atherosclerosis (fat deposits in the arteries), high blood pressure, blood platelet abnormalities, etc. It is an ocular emergency. Thus visiting an ophthalmologist when you experience a sudden and painless loss of vision is mandatory.
Retinal Vein Occlusion (RVO)
Figure 5: represents a normal retinal vein and a blockage in the vein.
The central retinal vein is responsible for draining the impure retinal blood out of the eye. The retinal vein occlusion occurs due to any block in the vein.
Similar to retinal artery occlusion, there are two types of retinal vein occlusions: central retinal vein occlusion and branch retinal vein occlusion. Some of the risk factors to develop retinal vein occlusion are age (patients older than 65 years), high blood pressure and blood sugar, smoking, etc.
Thus, people with high blood pressure and older than 65 should consult an ophthalmologist at least once a year.
Conclusion
Eyes are windows to the soul. Even a few moments of blurry vision can be so disturbing. Imagine having diminished vision throughout your life. It is our responsibility to take care of them.
In this review, few common retinal conditions such as diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, retinal detachment and retinal vascular occlusions have been discussed.
Retinal conditions cannot be cured but can be prevented. Thus, early screening of eyes is mandatory. Most often, eyes are not checked unless there is a vision problem. As mentioned above, there are some diseases that occur with no noticeable vision problems.
Thus, regular and comprehensive eye screening is mandatory. According to the American Academy of Optometry, any person at 40 years of age should take on a baseline eye examination, from 40 to 55 years should undertake eye examination every 2 to 4 years, from 55 to 64 should undertake eye examination every 1 to 3 years and above 65 years, should take an eye exam every year.
If you take care of your eyes, the eyes will take care of your life.